Dynamo-electric machine



Aug. 21, 1928. l,68l,780

N. PENSABENE DYNAMO ELECTRIC MACHINE Filed Dec. 27, 1927 i x .s e

O O W O O Patented Aug. 21, 1928.

i UNITED STATES- v 1581,780 P'ATENr. OFFICE..

NICOLO PENSABENE, OF LONDON, ENGLAND.

nYNAMo-ntncrmc MACHINE.

Application flled December 27, 1927, Serial No. 242,860, and in GreatBritain Hovcmbe25, 1926.

This invention relates to the construction of direct or continuouscurrent motors and dynamos of the totally enclosed type and has for itsobject to provide means whereby for a given weight and temperature risean output can be obtained larger than has been possible vup to now.

Various methods have been suggested for cooling totally enclosedmachines, these consisting merely in provldlng cooling plpes through themachlne carrying cool alr induced by a fan.

In an ordinary construction, howe'ver, where the casing or yoke is madeof magnetic material forming part of the 'magnet1c circuit, the positionof the pipes is not compatible with compactness of deslgn, there beingno room available inside the machine, especially when commutating polesare used, unless an otherwise unnecessary larger dlameter withconsequent larger weight of yoke and poles is adopted.

In my present invention make use of the split pole type of machine mwhich the supporting frame does not form part of the magnetic circuitandican be made of small steel section or of non-magnetic light weightmaterial as, for instance, aluminum.

i A machine of this type having a short magnetic circuit has already theadvantage of being light in weight and when used-totally enclosed lendsitself to a system of cooling whlch only implies a very small add1t1onto the weight.

In particular, this type of constructlon w1t h split poles and oneexcltmg co]] per pole 1s most suitable because in this ty e there arelarge empty spaces between the eld coil and the frame which are verysuitable for carrylng cooling pipes.

The type of construction referred to above is descrlbed in prior Britishspecification No. 189,862.

In the accompanymg drawmg 1t will be seen that for a 4-pole constructionthe magnetic system consists of four Sections bolted to a frame havingno magnetic fun'ction, each section representing two half-pole faces andtipks, twq half-pole bodies and a connecting o e. y Between two adjacentsections and the frame there are triangular-shaped 'emlpty es,

- spaces which would allow cooling tu which, passing through all thelength of the machine, are securely fixed between two flanges of thecase so as to prevent the cool air porting the field system,

.and only by way of example, 'Figura 1 and Figure 2 are givenrepresenting the transverse and longitudinal Sections of a 4-poletotally enclosed machine.

The case w is shown to have projecting ribs o on its inside surface inorder to sup ort the four magnetic Sections 8. It is seen tliat twoadjacent half sections form a magnetic pole split in the centre. Thefield coils 'w in this case are as many as the magnetic poles.

Between two sections 8 the case and the sides e of the field coils thecooling tubes t are shown. Othertubes can bepIaced between the ribs oreferred to above.

These tubes, which are made of good conducting and radiating material,are fixed between the flanges n of the case, as shown in Figure 2. Thearmature with winding and commutator is shown'in Figures 1 and 2 and ismarked a.

Inside the case a fan f1 drives the hot air throl'izgh the armature andcommutating poles and rows it outward so as to impinge on the coolingtubes.

' The cool air through these tubes is shown to be dl'iven from thedriving end of the machine and deflected by the covers C so as to coolthe end brackets of the machine.

It can be seen that the cooling surface of these tubes of small diametercan be as eat as several times the outside surface o the machine.

These tubes can be a thin material coated with. suitable heat-conductingpaint and any suitable shape to increase their radiating surface. Thetubes can be enclosed in a case through which the current of hot air tobe eooled will be circulated.

In a split pole machine having a number of field coils equal to doublethe number 'of poles the supporting case can be made still 'larger indiameter and the cooling pipes.

placed in the inside periphery o f the case.

This type of construction lends itself to a scheme of ventilationemploying a fan placed at the commutator end, the inspection doors Dbeing provided in the body of the case, as shown in the drawing.

A dynamo electric machine having an enclosing' casng with inwardlyextendmg spaced ribs on its inner Wall, a shaft and armaturepositionedcentrally of said casing, a split pole field element comprising aplurality of separate magnetic paths supported by sald ribs between saidcasing and armature, a plurality of Cooling tubes extending len thwiseof said casing between said ribs, sai armature having passages formedlengthwise thereof, means for causing fiow of air through said firstmentioned tubes for external cooling, and a separate means foreireulating air about said tubes and through the passages in thearmature in a closed internal cooling oircuit.

In testimony whereof I have aflixed my signature hereto this 6th day ofDecember, 1927.

NICOLO PENSABENE.

